In response to desires for extending the life of concrete drainage pipes and protecting against contamination of ground water supplies, water-proofing sheet linings comprised of PVC or the like have been developed for attachment to the interior bores of the pipes. Among the brands of linings which have been developed are those styled TROCAL and T-LOCK AMER-PLATE. The linings have increased resistance of pipes of corrosion from various acids, alkalis, salts, and other compounds normally found in sewage wastes and have decreased leakage to natural water supplies.
Although the linings have solved or greatly reduced certain problems of concrete pipe, other problems have been created by the linings particularly regarding the manufacture of lined pipe. Standard dry cast pipe-forming equipment has been greatly modified, particularly such harder to reach components thereof as the core, or inner form, which modifications can lead to holes in the pipe wall necessitating patching after the pipe has been formed. The conventional pipe-forming machines have long periods of down-time, with resultant production decreases, particularly due to the time normally required for attachment of the lining to the core. In standard methods of manufacture, the tension of the wires, which hold the lining to the core during manufacture, later tend to pull the lining out of the freshly compacted, or earth damp, concrete when the newly formed pipe is stripped from the forming mold. Also in standard methods of manufacture, the wires holding the lining to the core can tend to lie against the core such that they are very close to, or at, the inner surface of the formed pipe, such exposure necessitating patching to prevent rust problems.